Department of Chemistry , University of Torino , Via P. Giuria 5 , 10125 Torino , Italy.
Environ Sci Technol. 2019 Jul 16;53(14):7945-7963. doi: 10.1021/acs.est.9b00968. Epub 2019 Jun 26.
Photochemical processes taking place in surface fresh waters play an important role in the transformation of biorecalcitrant pollutants and some natural compounds and in the inactivation of microorganisms. Such processes are divided into direct photolysis, where a molecule is transformed following sunlight absorption, and indirect photochemistry, where naturally occurring photosensitizers absorb sunlight and produce a range of transient species that can transform dissolved molecules (or inactivate microorganisms). Photochemistry is usually favored in thoroughly illuminated shallow waters, while the dissolved organic carbon (DOC) acts as a switch between different photochemical pathways (direct photolysis, and indirect photochemistry triggered by different transient species). Various phenomena connected with climate change (water browning, changing precipitations) may affect water DOC and water depth, with implications for the kinetics of photoreactions and the associated transformation pathways. The latter are important because they often produce peculiar intermediates, with particular health and environmental impacts. Further climate-induced effects with photochemical implications are shorter ice-cover seasons and enhanced duration of summer stratification in lakes, as well as changes in the flow velocity of rivers that affect the photodegradation time scale. This contribution aims at showing how the different climate-related phenomena can affect photoreactions and which approaches can be followed to quantitatively describe these variations.
地表淡水发生的光化学过程在生物难降解污染物和一些天然化合物的转化以及微生物失活中起着重要作用。这些过程分为直接光解，即分子在吸收阳光后发生转化，以及间接光化学，其中天然存在的光敏剂吸收阳光并产生一系列瞬态物质，可转化溶解的分子（或使微生物失活）。光化学通常在充分光照的浅水中更为有利，而溶解有机碳 (DOC) 则是不同光化学途径（直接光解和由不同瞬态物质引发的间接光化学）之间的开关。与气候变化相关的各种现象（水变褐色、降水变化）可能会影响水的 DOC 和水深，从而影响光反应动力学及其相关的转化途径。后者很重要，因为它们通常会产生特殊的中间体，对健康和环境有特殊影响。与光化学有关的其他气候诱导效应包括冰盖季节缩短和湖泊夏季分层时间延长，以及影响光降解时间尺度的河流流速变化。本研究旨在展示不同的与气候相关的现象如何影响光反应，以及可以采用哪些方法来定量描述这些变化。
